1. Field of the Invention
This invention relates to an element for sealing two parts that can be rotated in relation to one another, with at least one sealing ring consisting of a permanently elastic material that is fixed to one of the two parts that can be rotated in relation to one another, and at least one sealing lip.
2. Description of the Prior Art
Commercial seals generally comprise a ring consisting of an elastic material fastened to one of the two parts that can be rotated in relation to one another, and that is provided with a sealing lip that is tightly pressed against a surface of the other of the two parts that can be rotated in relation to one another. For the sealing lip not to wear out prematurely, the contact surface should be as smooth as possible. A machined and/or polished surface area of the relevant rotating part is ordinarily used for this, which may also be protected against corrosion by a grease film. However, this arrangement has drawbacks:
In large bearings, in particular in plant construction, for example in the case of a pitch bearing of a wind energy system, but also in much medical equipment, the relevant rotating part is often so large that it is uneconomical to use stainless steel for this. The use of ordinary steel that rusts, on the other hand, leads to relatively rapid corrosion from the weathering of exposed bearings, since a protective grease film is quickly washed away by rain. Especially in coastal regions (wind energy systems) or even on the high seas (ships), the air is also very corrosive because of the salt water. However, as soon as corrosion sets in, the seal is damaged by the roughened surface it causes, and is finally destroyed.
In other uses, and in the medical technology sector, no grease film, or emergence of grease, is permissible, so that here also there is no corrosion protection, and without using a variety of stainless steel that substantially increases the cost of the equipment in question, corrosion would be unavoidable.
Many bearings can also be serviced only at great expense, so that it would be desirable for such applications to have available a special sealing element that does not have to be serviced, even in systems with a life expectation of 20 years.
The above considerations result in the problem behind the invention, of providing a seal that operates without wear even under rough or even corrosive environmental conditions, and/or without a protective grease film, for as long a time as possible.